Had AC Milan worn blue and Barcelona opted to wear traditional strips in their Champions League knockout stage meeting, it would have been difficult for fans to know whether or not they were watching a replay of last year’s semifinal matchup between Barça and Chelsea.

Milan executed the exact same tactics as the Blues did last season to move past the Catalan giants en route to the club’s first European title.

Chelsea, and now Milan, reminded fans that Barcelona is beatable. But the opposing team must first swallow its pride.

When Manchester United met Barça in the finals of the Champions League in 2009 and 2011, Sir Alex Ferguson was confident enough to put what he felt were his best 11 players on the field and play them straight up. It didn’t work.

But when Roberto Di Matteo went up again Barcelona last season, he kept his players behind the ball, packed the box and trusted his team to capitalize on counter attacks. It worked.

In the Rossoneri’s 2-0 victory, Massimiliano Allegri used the same tactics, and the Milan players executed them to perfection. Bleacher Report's Will Tidey gave the Rossoneri credit for their impressive defensive play.

Kevin-Prince Boateng’s goal was the result of a lucky bounce and fortunate non-call, but that does not diminish the quality of the finish. The next goal came after deft touches from M’Baye Niang and Stephan El Shaarawy set up another impressive strike from Sulley Muntari.

The key part of the strategy to beat Barcelona is to limit their opportunities on goal. The only way to do this is to keep players back in defense, thus limiting one’s own opportunities on goal, as well.

There were just 15 shots taken between the two teams, compared to 27 shots in the game between Schalke and Galatasaray that took place at the same time.

This is a testament to how well Milan’s defense and midfield played. They were never out of position and maintained the perfect balance between aggressively closing down the Barça players while not overcommitting.

Keeping a clean sheet against Barcelona is the most difficult task in club football, and the Milan back line deserves all the credit for accomplishing this.

On the other end, the attackers knew they would not receive many opportunities, and when presented with one, there would be no room for error.

These tactics are not new, and it is not a revelation that this is the strategy a team must use to beat Barça. However, it takes discipline, patience and confidence in front of goal to execute this blueprint.

Milan proved that it has all of these qualities and that it is capable of executing the necessary game plan at an extremely high level. It should not change a thing when it takes the field next to try and record one of the most shocking Champions League upsets in recent years.